Hodie prints the current date and time to stdout in Roman numerals, with grammatically correct Latin. Complete with Id., Kal., Non., pridie, postridie, bis, and all the other nice annoyances. As an option, it even provides you with current date according to Roman calendar -- that is 'ab urbe condita'; after Rome was built.
ICU provides a Unicode implementation, with functions for formatting numbers, dates, times, and currencies (according to locale conventions, transliteration, and parsing text in those formats). It provides flexible patterns for formatting messages, where the pattern determines the order of the variable parts of the messages, and the format for each of those variables. These patterns can be stored in resource files for translation to different languages. Included are more than 100 codepage converters for interaction with non-unicode systems.
Libxml2 is the XML C library developed for the Gnome project. The library code is portable (to Linux, Unix, Windows, embedded systems, etc.) and modular; most of the extensions can be compiled out. Libxml2 implements a number of existing standards related to markup languages, including the XML standard, Namespaces in XML, XML Base, Relax NG, RFC 2396, XPath, XPointer, HTML4, XInclude, SGML Catalogs, and XML Catalogs. In most cases, libxml tries to implement the specifications in a relatively strict way. To some extent, it provides support for the following specifications, but doesn't claim to implement them: DOM, FTP client, HTTP client, and SAX2. Support for W3C XML Schemas is in progress. It includes xmllint, a command line XML validator.
Lua is a programming language originally designed for extending applications, but also frequently used as a general-purpose, stand-alone language. It combines simple procedural syntax (similar to Pascal) with powerful data description constructs based on associative arrays and extensible semantics. It is dynamically typed, interpreted from bytecodes, and has automatic memory management, making it ideal for configuration, scripting, and rapid prototyping. It is implemented as a small library of C functions, written in ANSI C, and compiles unmodified in all known platforms. The implementation goals are simplicity, efficiency, portability, and low embedding cost. It has been used on games such as World of Warcraft, FarCry and Angry Birds, among others.
Libxslt is a C library for GNOME which allows developers to work with XSLT. It is based on libxml for XML parsing, tree manipulation, and XPath support. Also included is 'xsltproc', a command line XSLT processor. The library is written in plain C, making as few assumptions as possible, and sticking closely to ANSI C/POSIX for easy embedding. It should work on Linux, Unix, and Windows. Though not designed primarily with performances in mind, libxslt seems to be a relatively fast processor. It also include full support for the EXSLT set of extension functions as well as some common extensions present in other XSLT engines.
DOMC is a lightweight implementation of the Document Object Model (DOM) in ANSI C as specified in the W3C DOM Core Level 1 recommendation. When coupled with the Expat XML Parser Toolkit, DOMC can load, store, build, and directly manipulate XML documents represented as a tree in memory.
The libmba package is a collection of mostly independent C modules potentially useful to any project. There are the usual ADTs including a linkedlist, hashmap, pool, stack, and varray, a flexible memory allocator, CSV parser, path canonicalization routine, I18N text abstraction, configuration file module, portable semaphores, condition variables, and more. The code is designed so that individual modules can be integrated into existing codebases rather than requiring the user to commit to the entire library. The code has no typedefs, few comments, and extensive man pages and HTML documentation.